U.S. patent number 7,248,898 [Application Number 10/508,557] was granted by the patent office on 2007-07-24 for radio device, transmission/reception directivity control method, and transmission/reception directivity control program.
This patent grant is currently assigned to Sanyo Electric Co., Ltd.. Invention is credited to Yoshiharu Doi, Akira Ishida.
United States Patent |
7,248,898 |
Doi , et al. |
July 24, 2007 |
Radio device, transmission/reception directivity control method,
and transmission/reception directivity control program
Abstract
A radio device includes an array antenna including a plurality
of antennas; an adaptive array processing unit multiplying signals
provided from the respective antennas of the array antenna by
receive weights, and thereby extracting a signal received from
desired another radio device; a switch circuit provided
corresponding to at least one of the plurality of antennas for
providing the signal received from the corresponding antenna to the
reception signal processing unit in a receive operation; and a
transmission amplifier amplifying and providing a modulated
transmission signal to the first switch circuit corresponding to
the one of the plurality of antennas.
Inventors: |
Doi; Yoshiharu (Gifu,
JP), Ishida; Akira (Hirakata, JP) |
Assignee: |
Sanyo Electric Co., Ltd.
(Osaka, JP)
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Family
ID: |
28449121 |
Appl.
No.: |
10/508,557 |
Filed: |
March 11, 2003 |
PCT
Filed: |
March 11, 2003 |
PCT No.: |
PCT/JP03/02884 |
371(c)(1),(2),(4) Date: |
June 17, 2005 |
PCT
Pub. No.: |
WO03/081808 |
PCT
Pub. Date: |
October 02, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060014497 A1 |
Jan 19, 2006 |
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Foreign Application Priority Data
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Mar 22, 2002 [JP] |
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2002-081458 |
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Current U.S.
Class: |
455/562.1;
342/368; 342/374; 342/377; 455/561; 455/63.4; 455/69 |
Current CPC
Class: |
H01Q
1/246 (20130101); H01Q 3/24 (20130101); H01Q
3/26 (20130101); H04B 7/0602 (20130101); H04B
7/0808 (20130101); H04B 7/0848 (20130101); H04W
52/42 (20130101); H04B 7/0608 (20130101) |
Current International
Class: |
H04B
1/38 (20060101); H04M 1/00 (20060101) |
Field of
Search: |
;455/562.1,69,63.4,561,67.16,456.1 ;342/377,374,368,373 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1304586 |
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Jul 2001 |
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CN |
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1041839 |
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Oct 2000 |
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EP |
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11-252614 |
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Sep 1999 |
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JP |
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2000-216724 |
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Aug 2000 |
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JP |
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2001-251233 |
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Sep 2001 |
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JP |
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WO 99/52226 |
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Oct 1999 |
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WO |
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Other References
Personal Handy Phone System ARIB Standard RCR STD-28, Association
of Radio Industries and Businesses, May 2004. cited by other .
Nobuyoshi Kikuma, "Adaptive Signal Processing by Array Antenna",
Kagaku Gijutsu Shuppan pp. 35-49, Nov. 1998. cited by
other.
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Primary Examiner: Anderson; Matthew
Assistant Examiner: Pham; Tuan
Attorney, Agent or Firm: McDermott Will & Emery LLP
Claims
The invention claimed is:
1. A radio device comprising: an array antenna including a
plurality of antennas; a reception signal processing unit
multiplying signals provided from said respective antennas of said
array antenna by reception weights, and thereby extracting a signal
received from desired another radio device; first switch means
provided corresponding to at least one of said plurality of
antennas for providing the signal received from the corresponding
antenna to said reception signal processing unit in a receive
operation; and a transmission signal processing unit modulating and
providing a transmission signal to said first switch means
corresponding to the one antenna of said plurality of antennas,
wherein said first switch means provides the signal received from
said transmission signal processing unit to said corresponding
antenna in a transmission operation, said first switch means are
provided corresponding to said plurality of antennas, respectively,
said radio device further comprising: reception level measuring
means for measuring reception levels of the signals transmitted
from a terminal to be communicated with said radio device and
received by said plurality of antennas, respectively; storage means
for storing results of the measurements of said reception level
measuring means; antenna selecting means for selecting the antenna
having the maximum reception level from said plurality of antennas
based on information stored in said storage means; and second
switch means for providing the signal provided from said
transmission signal processing unit to said first switch means
corresponding to the selected antenna in accordance with a result
of selection by said antenna selecting means.
2. A radio device comprising: an array antenna including a
plurality of antennas; a reception signal processing unit
multiplying signals provided from said respective antennas of said
array antenna by reception weights, and thereby extracting a signal
received from desired another radio device; first switch means
provided corresponding to at least one of said plurality of
antennas for providing the signal received from the corresponding
antenna to said reception signal processing unit in a receive
operation; and a transmission signal processing unit modulating and
providing a transmission signal to said first switch means
corresponding to the one antenna of said plurality of antennas,
wherein said first switch means provides the signal received from
said transmission signal processing unit to said corresponding
antenna in a transmission operation, the radio device further
comprising: reception level measuring means for measuring the
reception level of the signal received by said plurality of
antennas from a desired terminal to be communicated with said radio
device; storage means for storing a result of the measurement by
said reception level measuring means and a transmission power level
required in accordance with said reception level; and transmission
power calculating means for controlling an output level of said
transmission signal processing unit in accordance with the
transmission power level determined based on the information stored
in said storage means, wherein said reception level measuring means
further measures a level of interference with respect to
communication performed with the desired terminal, said storage
means stores the transmission power level required in accordance
with said reception level and said interference level, and said
interference level, and said transmission power calculating means
determines said transmission power level in accordance with said
interference level and said reception level.
3. A radio device comprising: an array antenna including a
plurality of antennas; a reception signal processing unit
multiplying signals provided from said respective antennas of said
array antenna by reception weights, and thereby extracting a signal
received from desired another radio device; first switch means
provided corresponding to at least one of said plurality of
antennas for providing the signal received from the corresponding
antenna to said reception signal processing unit in a receive
operation; and a transmission signal processing unit modulating and
providing a transmission signal to said first switch means
corresponding to the one antenna of said plurality of antennas,
wherein said first switch means provides the signal received from
said transmission signal processing unit to said corresponding
antenna in a transmission operation, said first switch means are
provided corresponding to said plurality of antennas, respectively,
said radio device further comprising: reception level measuring
means for measuring levels of the signals sent from a terminal to
be communicated with said radio device and received by said
plurality of antennas; storage means for storing a result of the
measurement of said reception level measuring means and a
transmission power level required in accordance with the reception
level; transmission power calculating means for controlling an
output level of said transmission signal processing unit in
accordance with the transmission power level determined based on
the information stored in said storage means; antenna selecting
means selecting the antenna having the maximum reception level from
said plurality of antennas based on the information stored in said
storage means; and second switch means providing the signal
provided from said transmission signal processing unit to said
first switch means corresponding to the selected antenna in
accordance with a result of selection of said antenna selecting
means.
4. The radio device according to claim 3, wherein said reception
level measuring means further measures a level of interference with
respect to communication performed with the desired terminal, said
storage means stores the transmission power level required in
accordance with said reception level and said interference level,
and said interference level, and said transmission power
calculating means determines said transmission power level in
accordance with said interference level and said reception
level.
5. A transmission and reception directivity control method of a
radio device with an array antenna including a plurality of
antennas, comprising the steps of: multiplying signals provided
from said respective antennas of said array antenna by reception
weights, and thereby performing separation and extraction of a
signal received from desired another radio device; modulating a
transmission signal; providing said modulated transmission signal
to one of said plurality of antennas; measuring reception levels of
signals sent from a desired terminal to be communicated with said
radio device and received by said plurality of antennas; storing
said reception levels and transmission power levels required
according to the reception levels; determining the transmission
power level based on said reception level and the transmission
power level required according to the reception level; controlling
a level of output of said modulated transmission signal according
to said determined transmission power level; and measuring the
level of interference with respect to the communication performed
with said desired terminal, wherein said step of storing includes
the step of: storing the transmission power level required
according to said measured reception level and said interference
level, and said interference level, and said step of determining
said transmission power level includes the step of: determining
said transmission power level according to the interference level
and the reception level.
6. A transmission and reception directivity control method of a
radio device with an array antenna including a plurality of
antennas, comprising the steps of: multiplying signals provided
from said respective antennas of said array antenna by reception
weights, and thereby performing separation and extraction of a
signal received from desired another radio device; modulating a
transmission signal; providing said modulated transmission signal
to one of said plurality of antennas; measuring levels of signals
sent from a desired terminal to be communicated with said radio
device and received by said plurality of antennas; storing said
measured reception levels and transmission power levels required
according to said reception levels; determining the transmission
power level based on said stored reception level and the
transmission power level required according to said reception
level; controlling an output level of said transmission signal
according to said determined transmission power level; selecting
the antenna having the maximum reception level from said plurality
of antennas based on said measured reception levels; providing said
transmission signal to said selected antenna; and measuring the
level of interference with respect to the communication performed
with said desired terminal, wherein said step of storing includes
the step of: storing the transmission power level required
according to said reception level and said interference level, and
said interference level, and said step of determining said
transmission power level includes the step of: determining said
transmission power level according to the interference level and
the reception level.
7. A computer program product including a computer readable medium
storing a transmission and reception directivity control program of
a radio device with an array antenna including a plurality of
antennas, said program causing a computer to execute the steps of:
multiplying signals provided from said respective antennas of said
array antenna by reception weights, and thereby performing
separation and extraction of a signal received from desired another
radio device; modulating a transmission signal; providing said
modulated transmission signal to one of said plurality of antennas;
measuring reception levels of signals sent from a desired terminal
to be communicated with said radio device and received by said
plurality of antennas; storing said reception levels and
transmission power levels required according to the reception
levels; determining the transmission power level based on said
reception level and the transmission power level required according
to the reception level; controlling a level of output of said
modulated transmission signal according to said determined
transmission power level; and measuring the level of interference
with respect to the communication performed with said desired
terminal, wherein said step of storing includes the step of:
storing the transmission power level required according to said
measured reception level and said interference level, and said
interference level, and said step of determining said transmission
power level includes the step of: determining said transmission
power level according to the interference level and the reception
level.
8. A computer program product including a computer readable medium
storing a transmission and reception directivity control program of
a radio device with an array antenna including a plurality of
antennas, said program causing a computer to execute the steps of:
multiplying signals provided from said respective antennas of said
array antenna by reception weights, and thereby performing
separation and extraction of a signal received from desired another
radio device; modulating a transmission signal; providing said
modulated transmission signal to one of said plurality of antennas;
measuring levels of signals sent from a desired terminal to be
communicated with said radio device and received by said plurality
of antennas; storing said measured reception levels and
transmission power levels required according to said reception
levels; determining the transmission power level based on said
stored reception level and the transmission power level required
according to said reception level; controlling an output level of
said transmission signal according to said determined transmission
power level; selecting the antenna having the maximum reception
level from said plurality of antennas based on said measured
reception levels; providing said transmission signal to said
selected antenna; and measuring the level of interference with
respect to the communication performed with said desired terminal,
wherein said step of storing includes the step of: storing the
transmission power level required according to said reception level
and said interference level, and said interference level, and said
step of determining said transmission power level includes the step
of: determining said transmission power level according to the
interference level and the reception level.
Description
TECHNICAL FIELD
The present invention relates to a radio device, and particularly
to a radio device, a transmission and reception directivity control
method and a transmission and reception directivity control
program, which can transmit and receive signals with directivity by
performing adaptive array processing.
DESCRIPTION OF THE BACKGROUND ART
In recent years, mobile communication systems such as a PHS
(Personal Handy phone System) have been rapidly developed, and
these systems have employed a TDMA method, in which one frame (5
milliseconds) formed of four slots (625 microseconds per slot) is
used as a basic unit for transmission and reception. This TDMA
method of the PHS has been standardized, e.g., as a "second
generation cordless communication system).
In the communication system of the PHS, a signal in one frame is
divided into eight slots, which are divided into a first half
including four slots for reception as well as a latter half
including four slots for transmission.
Each slot is formed of 120 symbols. For example, the signal in one
frame is handled such that three slot sets each formed of one
reception slot and one transmission slot are allocated to traffic
channels for three users, respectively, and remaining one set of
slots is allocated to a control channel.
According to controlling procedures for establishing
synchronization in the PHS, a link channel is first established by
a control channel, and processing of measuring interference wave
(U-waves: Undesired waves) is performed. Further processing is
performed to set communication conditions with allocated channels,
and thereafter, the speech communication starts. The above
procedures are disclosed in detail by standards of the PHS, and
particularly by the second generation cordless communication system
standards RCR STD-28 issued by Association of Radio Industries and
Businesses.
FIG. 21 illustrates a communication sequence flow of the PHS.
Referring to FIG. 21, this flow will now be briefly described.
By using a C-channel (Control channel: CCH), a link channel
establishment request signal (LCH establishment request signal) is
sent from a PHS terminal to a base station. The PHS base station
detects an empty channel (i.e., empty traffic channel (empty
T-channel)), and sends a link channel allocation signal (LCH
allocation signal) to the PHS terminal side via the C-channel.
On the PHS terminal side, it is determined based on link channel
information received from the PHS base station whether interference
wave signals of a predetermined power or higher are received or not
on a designated T-channel, and thus U-wave measurement and carrier
sense are performed. When interference wave signals of the
predetermined power or higher are not detected, i.e., when another
PHS base station is not using the designated T-channel, a
synchronous burst signal is sent to the base station by the
designated T-channel, and a synchronous burst signal is also
returned from the base station to the terminal to establish the
synchronization.
When interference wave signals of the predetermined power or higher
are detected on the designated T-channel, i.e., when another PHS
base station is using the designated T-channel, the PHS terminal
repeats the control procedures starting from issuance of the
request signal for the link channel establishment.
As described above, the PHS connects the communication channel
between the terminal and the base station by using the channel,
which can provide good communication characteristics suppressing
the interference waves.
For maintaining a good communication quality by suppressing an
influence by communication of another base station, the PHS may
perform transmission and reception with directivity when the base
station transmits a signal to the terminal or receives a signal
therefrom.
In the PHS and others, a PDMA (Path Division Multiple Access)
system is available for increasing an efficiency of use of wave
frequencies. In the PDMA, spatial multiple connection can be
achieved between mobile radio terminal devices (terminals) of a
plurality of users and the radio base station (base station) via a
plurality of paths, which are formed by spatially dividing the same
time slot of the same frequency.
For example, an adaptive array technology has been employed for
achieving the directivity in the transmission and reception and
achieving the PDMA system described above. The adaptive array
processing can accurately extracts signals from a desired terminal
by adaptive control, which is performed by calculating a weight
vector (receive weight vector) formed of receive coefficients
(weights) for respective antennas of the base station based on the
signal received from the terminal, and thus, by multiplying the
reception signals of the plurality of antennas by respective
elements of the receive weight vector.
By the adaptive array processing, an uplink signal sent from the
antenna of each user terminal is received by the array antenna of
the base station, and the signal thus received is separated and
extracted with a receive directivity.
The transmission signals (i.e., signals to be sent) are processed
such that signals, which are produced by multiplying the
transmission signal by respective elements of the transmission
weight vector calculated from the receive weight vector, are
transmitted from the plurality of antennas, and thereby a downlink
signal to be sent from the base station to the terminal is
transmitted with a send directivity with respect to the antenna of
the terminal.
The above adaptive array processing is well known, and is
specifically disclosed in Nobuyoshi Kikuma "Chapter 3: MMSE
Adaptive Array" in "Adaptive Signal Processing by Array Antenna",
Kagaku Gijutsu Shuppan, Nov. 25, 1998, pp. 35 49. Therefore, an
operation principle thereof is not described in this
specification.
Among the signals received in the PDMA system, a desired signal is
identified in the following manner. A radio signal transmitted
between a terminal such as a cellular phone and a base station is
divided into a plurality of frames, and thus has a so-called frame
structure when it is transmitted. Each frame includes eight slots
formed of, e.g., four slots for uplink communication and four slots
for downlink communication. This slot signal is basically formed of
a preamble formed of a signal series, which is known on a receiver
side, and data (such as voice) formed of a signal series, which is
unknown on the receiver side.
The preamble signal series includes a signal series (reference
signal such as a unique word signal) of information for determining
whether the sender on the other end is the desired party for the
receiver side or not. For example, the adaptive array radio base
station performs weight vector control (determination of weight
coefficients) to extract a signal, which is presumed to include a
signal series corresponding to the desired party on the other end,
based on a comparison between the unique word signal obtained from
the memory and the received signal series.
Further, each frame includes the foregoing unique word signal
(reference signal) section, and is further configured to allow
error detection with cyclic codes (CRC: Cyclic Redundancy
Check).
FIG. 22 is a conceptual view illustrating a state of communication
between a conventional radio device and a base station.
In an example illustrated in FIG. 22, the communication is being
performed between a radio base station CS1 and a radio terminal
device PS1, and the communication is also being performed between
another radio base station CS2 neighboring to radio base station
CS1 and another radio terminal device PS2.
In FIG. 22, it is assumed that non-directional transmission and
reception is performed for both the communication from the radio
terminal device to the base station, which will be referred to as
"uplink communication" hereinafter, and the communication from the
radio base station to the radio terminal device, which will be
referred to as "downlink communication" hereinafter.
In the structure illustrated in FIG. 22, a problem of interference
is liable to occur when the communication in a peripheral cell,
which is a communication region of radio base station CS2, is being
performed with the same frequency and at the same time as the
communication in a cell, which is a communication region of radio
base station CS1.
More specifically, in the uplink communication, the quality of the
uplink communication in the station's own cell is impaired by the
interference from the peripheral cell.
Likewise, in the downlink communication, the interference is
applied to the peripheral cell to impair the downlink quality of
the terminal, which is communicating in the peripheral cell.
In FIG. 22, arrows with dotted lines indicate interference signals
occurring between radio base station CS1 and radio terminal device
PS2.
For suppressing the interference during the simultaneous
communication with the same frequency, the adaptive array
transmission and reception already described may be performed.
However, if the adaptive array transmission and reception is
performed in both the uplink communication and the downlink
communication, this increases an installation cost of the base
station.
More specifically, for performing the adaptive array processing in
the downlink communication, an expensive high-power amplifier is
required for every antenna of the base station, resulting in the
high installation cost.
Further, each base station requires a signal processing circuit for
controlling the downlink directivity, which further increases the
cost.
If the FDD (Frequency Division Duplex) system is employed, it is
difficult to control accurately the directivity.
In other words, a difference occurs in amount of rotation of a
phase, which is caused when passing through a propagation path,
between the uplink communication and the downlink communication.
Therefore, it is difficult to control the directivity in the
downlink communication based on information related to the
directivity obtained in the uplink communication so that accurate
control of the directivity is difficult, and interference with the
peripheral cell increases.
The invention has been developed for overcoming the above problems,
and it is an object of the invention to provide a radio device, a
transmission and reception directivity control method and a
transmission and reception directivity control program, which can
reduce an installation cost of the base station, and can suppress
interference signals affecting a peripheral cell.
DISCLOSURE OF THE INVENTION
In summary, the invention includes an array antenna including a
plurality of antennas; a reception signal processing unit
multiplying signals provided from the respective antennas of the
array antenna by reception weights, and thereby extracting a signal
received from desired another radio device; switch means provided
corresponding to at least one of the plurality of antennas for
providing the signal received from the corresponding antenna to the
reception signal processing unit in a reception operation; and a
transmission signal processing unit modulating and providing a
transmission signal to the first switch means corresponding to the
one antenna of the plurality of antennas. The first switch means
provides the signal received from the transmission signal
processing unit to the corresponding antenna in a transmission
operation.
Preferably, the first switch means are provided corresponding to
the plurality of antennas, respectively, and the radio device
further includes reception level measuring means for measuring
reception levels of the signals transmitted from a terminal to be
communicated with the radio device and received by the plurality of
antennas, respectively; storage means for storing results of the
measurements of the reception level measuring means; antenna
selecting means for selecting the antenna having the maximum
reception level from the plurality of antennas based on information
stored in the storage means; and second switch means for providing
the signal provided from the transmission signal processing unit to
the first switch means corresponding to the selected antenna in
accordance with a result of selection by the antenna selecting
means.
Preferably, the radio device further includes reception level
measuring means for measuring the reception level of the signal
received by the plurality of antennas from a desired terminal to be
communicated with the radio device; storage means for storing a
result of the measurement by the reception level measuring means
and a transmission power level required in accordance with the
reception level; and transmission power calculating means for
controlling an output level of the transmission signal processing
unit in accordance with the transmission power level determined
based on the information stored in the storage means.
Preferably, the reception level measuring means further measures a
level of interference with respect to communication with the
desired terminal, the storage means stores the transmission power
level required in accordance with the reception level and the
interference level, and the interference level, and the
transmission power calculating means determines the transmission
power level in accordance with the interference level and the
reception level.
Preferably, the first switch means are provided corresponding to
the plurality of antennas, respectively, and the radio device
further includes reception level measuring means for measuring
levels of the signals sent from a terminal to be communicated with
the radio device and received by the plurality of antennas; storage
means for storing a result of the measurement of the reception
level measuring means and a transmission power level required in
accordance with the reception level; transmission power calculating
means for controlling an output level of the transmission signal
processing unit in accordance with the transmission power level
determined based on the information stored in the storage means;
antenna selecting means selecting the antenna having the maximum
reception level from the plurality of antennas based on the
information stored in the storage means; and second switch means
providing the signal provided from the transmission signal
processing unit to the first switch means corresponding to the
selected antenna in accordance with a result of selection of the
antenna selecting means.
Preferably, the reception level measuring means further measures a
level of interference with respect to communication performed with
the desired terminal, the storage means stores the transmission
power level required in accordance with the reception level and the
interference level, and the interference level, and the
transmission power calculating means determines the transmission
power level in accordance with the interference level and the
reception level.
According to another aspect of the invention, a transmission and
reception directivity control method of a radio device with an
array antenna including a plurality of antennas, includes the steps
of multiplying signals provided from the respective antennas of the
array antenna by reception weights, and thereby performing
separation and extraction of a signal received from desired another
radio device; modulating a transmission signal; and providing the
modulated transmission signal to one of the plurality of
antennas.
Preferably, the method further includes the steps of measuring
reception levels of signals sent from a desired terminal to be
communicated with the radio device and received by the plurality of
antennas; storing the measured reception levels; selecting the
antenna having the maximum reception level from the plurality of
antennas based on the stored reception levels; and providing the
modulated transmission signal to the selected antenna.
Preferably, the method further includes the steps of measuring
reception levels of signals sent from a desired terminal to be
communicated with the radio device and received by the plurality of
antennas; storing the reception levels and transmission power
levels required according to the reception levels; determining the
transmission power level based on the reception level and the
transmission power level required according to the reception level;
and controlling a level of output of the modulated transmission
signal according to the determined transmission power level.
Preferably, the method further includes the step of measuring the
level of interference with respect to the communication performed
with the desired terminal. The step of storing includes the step of
storing the transmission power level required according to the
measured reception level and the interference level, and the
interference level. The step of determining the transmission power
level includes the step of determining the transmission power level
according to the interference level and the reception level.
Preferably, the method further includes the steps of measuring
levels of signals sent from a desired terminal to be communicated
with the radio device and received by the plurality of antennas;
storing the measured reception levels and transmission power levels
required according to the reception levels; determining the
transmission power level based on the stored reception level and
the transmission power level required according to the reception
level; controlling an output level of the transmission signal
according to the determined transmission power level; selecting the
antenna having the maximum reception level from the plurality of
antennas based on the measured reception levels; and providing the
transmission signal to the selected antenna.
Preferably, the method further includes the step of measuring the
level of interference with respect to the communication performed
with the desired terminal. The step of storing includes the step of
storing the transmission power level required according to the
reception level and the interference level, and the interference
level. The step of determining the transmission power level
includes the step of determining the transmission power level
according to the interference level and the reception level.
According to still another aspect of the invention, a transmission
and reception directivity control program of a radio device with an
array antenna including a plurality of antennas causes a computer
to execute the steps of multiplying signals provided from the
respective antennas of the array antennas by reception weights, and
thereby performing separation and extraction of a signal received
from desired another radio device; modulating a transmission
signal; and providing the modulated transmission signal to one of
the plurality of antennas.
Preferably, the program further causes the computer to execute the
steps of measuring reception levels of signals sent from a terminal
to be communicated with the radio device and received by the
plurality of antennas; storing the measured reception levels;
selecting the antenna having the maximum reception level from the
plurality of antennas based on the stored reception levels; and
providing the modulated transmission signal to the selected
antenna.
Preferably, the program further causes the computer to execute the
steps of measuring reception levels of signals sent from a desired
terminal to be communicated with the radio device and received by
the plurality of antennas; storing the reception levels and
transmission power levels required according to the reception
levels; determining the transmission power level based on the
reception level and the transmission power level required according
to the reception level; and controlling a level of output of the
modulated transmission signal according to the determined
transmission power level.
Preferably, the program further causes the computer to execute the
step of measuring the level of interference with respect to the
communication performed with the desired terminal. The step of
storing includes the step of storing the transmission power level
required according to the measured reception level and the
interference level, and the interference level. The step of
determining the transmission power level includes the step of
determining the transmission power level according to the
interference level and the reception level.
Preferably, the program further causes the computer to execute the
steps of measuring levels of signals sent from a desired terminal
to be communicated with the radio device and received by the
plurality of antennas; storing the measured reception levels and
transmission power levels required according to the reception
levels; determining the transmission power level based on the
stored reception level and the transmission power level required
according to the reception level; controlling an output level of
the transmission signal according to the determined transmission
power level; selecting the antenna having the maximum reception
level from the plurality of antennas based on the measured
reception levels; and providing the transmission signal to the
selected antenna.
Preferably, the program further causes the computer to execute the
step of measuring the level of interference with respect to the
communication performed with the desired terminal. The step of
storing includes the step of storing the transmission power level
required according to the reception level and the interference
level, and the interference level. The step of determining the
transmission power level includes the step of determining the
transmission power level according to the interference level and
the reception level.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a conceptual view illustrating a directivity of uplink
communication in a radio system according to a first embodiment of
the invention.
FIG. 2 illustrates directivity control in downlink communication
according to the first embodiment of the invention.
FIG. 3 is a schematic block diagram illustrating a structure of a
radio base station 1000 for performing the directivity control
illustrated in FIGS. 1 and 2.
FIG. 4 is a flow chart illustrating an operation of radio base
station 1000 shown in FIG. 3.
FIG. 5 is a schematic block diagram illustrating a structure of a
radio base station 1200 of a modification of the first
embodiment.
FIG. 6 is a flow chart illustrating an operation of radio base
station 1200 of the modification of the first embodiment
illustrated in FIG. 5.
FIG. 7 is a conceptual view illustrating a transmission directivity
in uplink communication according to the second embodiment.
FIG. 8 is a conceptual view illustrating the transmission
directivity in the downlink communication as well as a range of
waves.
FIG. 9 is a schematic block diagram illustrating a structure of a
radio base station 2000 according to the second embodiment.
FIG. 10 is a flowchart illustrating an operation of radio base
station 2000 according to the second embodiment of the invention
illustrated in FIG. 9.
FIG. 11 is a schematic block diagram illustrating a structure of a
radio base station 2200, which is a modification of radio base
station 2000 according to the second embodiment illustrated in FIG.
9.
FIG. 12 is a flowchart illustrating an operation of radio base
station 2200 of the modification of the second embodiment
illustrated in FIG. 11.
FIG. 13 is a first conceptual view illustrating a method of
controlling a transmission power and a transmission directivity
according to a third embodiment of the invention.
FIG. 14 is a second conceptual view illustrating the method of
controlling the transmission power and the transmission directivity
according to the third embodiment.
FIG. 15 is a third conceptual view illustrating the method of
controlling the transmission power and the transmission directivity
according to the third embodiment.
FIG. 16 is a fourth conceptual view illustrating the method of
controlling the transmission power and the transmission directivity
according to the third embodiment.
FIG. 17 is a schematic block diagram illustrating a structure of a
radio base station 3000 according to the third embodiment.
FIG. 18 is a flowchart illustrating an operation of radio base
station 3000 according to the third embodiment of the
invention.
FIG. 19 is a schematic block diagram illustrating a structure of a
radio base station 3200 of a modification of the third
embodiment.
FIG. 20 is a flowchart illustrating an operation of radio base
station 3200 of the modification of the third embodiment
illustrated in FIG. 19.
FIG. 21 illustrates a communication sequence flow of a PHS.
FIG. 22 is a conceptual view illustrating a state of communication
between a conventional radio device and a base station.
BEST MODES FOR CARRYING OUT THE INVENTION
Embodiments of the invention will now be described with reference
to the drawings. In the following description, the same or
corresponding portions bear the same reference numbers, and
description thereof is not repeated.
FIRST EMBODIMENT
FIG. 1 is a conceptual view for illustrating a directivity in
uplink communication of a radio system according to a first
embodiment of the invention. FIG. 2 illustrates directivity control
in downlink communication according to the first embodiment of the
invention.
The invention is not necessarily restricted to the PHS, but the PHS
will now be described as an example of a radio system according to
the invention.
Referring first to FIG. 1, a radio base station 1000 of the first
embodiment performs adaptive array processing for performing
reception with a directivity when it receives a signal from a user
terminal PSI in its own cell, i.e., when base station 1000 performs
uplink communication.
This structure can suppress an interference signal from a user
terminal PS2 in a peripheral cell, and therefore can prevent
lowering of communication quality of the user in its own cell.
Referring to FIG. 2, radio base station 1000 according to the first
embodiment of the invention performs non-directional transmission
when base station 1000 transmits a signal to user terminal PS1 in
its own cell, i.e., when base station 1000 performs downlink
communication. Thus, the downlink communication is performed
without performing the adaptive array processing, and therefore an
adaptive array processing circuit for the downlink communication is
not required so that an installation cost of such a circuit can be
eliminated.
FIG. 3 is a schematic block diagram illustrating a structure of
radio base station 1000 performing the directivity control already
described with reference to FIGS. 1 and 2.
Referring to FIG. 3, radio base station 1000 includes an adaptive
array antenna 10 having a plurality of antennas #1-#n, a switch
circuit 12.1, which sends a signal received by antenna #1 to radio
base station 1000 for performing the adaptive array processing in
the receive operation, and provides selectively a transmission
signal (i.e., signal to be sent) to antenna #1 in the transmission
operation, an adaptive array processing unit 20, which receives the
signal sent from switch circuit 12.1 and signals sent from antennas
#2-#n, perform the adaptive array processing on the signals
received by the plurality of antennas #1-#n, and thereby performs
selective separation and extraction of the signal sent from a
desired user terminal, a demodulator 30, which receives an output
of adaptive array processing unit 20, and performs demodulation and
extraction of a baseband signal, a modulator 40, which receives and
modulates a baseband signal for transmission, a transmission
amplifier 50, which receives an output of modulator 40, amplifies a
transmission signal and provides the amplified signal to switch
circuit 12.1 corresponding to antenna #1, and a control unit CNP
controlling operations of switch circuit 12.1, adaptive array
processing unit 20, demodulator 30, modulator 40 and transmission
amplifier 50. In FIG. 3, one antenna transmitting the transmission
signal is antenna #1. However, the invention is not restricted to
this, and the one antenna may be appropriately selected from the
plurality of antennas #1-#n.
Functions of radio base station 1000, which will be described
below, may be achieved by a processor, which is arranged in control
unit CNP for successively executing a series of procedures
described by a computer program, and particularly by controlling
operations of various components of radio base station 1000 by this
processor, although the invention is not restricted to this. This
program can be installed into control portion CNP from a record
medium bearing the program.
FIG. 4 is a flowchart illustrating the operation of radio base
station 1000 illustrated in FIG. 3.
Referring to FIG. 4, when speech communication processing starts
(step S100), communication establishing processing is performed for
starting the speech communication (S102). For receiving an uplink
signal, control unit CNP controls switch circuit 12.1 and adaptive
array processing unit 20 to perform adaptive array receive
processing on the uplink signal (step S104).
When a downlink signal is to be sent to the user terminal, which
sent the uplink signal, control unit CNP controls switch circuit
12.1 to transmit a signal provided from transmission amplifier 50
via antenna #1 (step S106).
Subsequently, it is determined whether the speech communication
state is already finished or not (step S108). If not, the
processing returns to step S104.
When it is determined in step S108 that the speech communication
state is already finished, the communication processing ends (step
S110).
In the uplink communication, the above structure performs the
adaptive array processing, and therefore can maintain high
communication quality by suppressing interference signals coming
from a peripheral cell.
For the downlink communication, the adaptive array processing is
eliminated, and therefore the adaptive array processing circuit can
be eliminated so that the installation cost of the radio base
station can be reduced.
MODIFICATION OF THE FIRST EMBODIMENT
According to the first embodiment, the antenna used for the
non-directional transmission is a predetermined one antenna (e.g.,
antenna #1).
However, antenna #1 among the plurality of antennas #1-#n may not
be the optimum antenna for the communication with a certain user
terminal PS1.
According to the modification of the first embodiment, the antenna
which is most suitable for communication with the radio terminal
PS1 within the station's own cell is selected and used in the
downlink communication.
FIG. 5 is a schematic block diagram illustrating a structure of a
radio base station 1200 of the modification of the first
embodiment.
The structure of radio base station 1200 differs from that of radio
base station 1000 in that switch circuits 12.1-12.n are provided
for all antennas #1-#n, respectively, and these switch circuits
12.1-12.n selectively transmit signals sent from antennas #1-#n to
internal circuits of radio base station 1200, or provides signals
sent from internal circuits of radio base station 1200 to antennas
#1-#n, respectively.
Radio base station 1200 further includes a reception level
measuring device 60, which receives signals from switch circuits
12.1-12.n, and measures the reception signal levels, a memory 70
storing the reception level of each antenna obtained by reception
level measuring device 60, an antenna selecting device 80 selecting
the antenna of the highest reception level based on the information
stored in memory 70, and a switch circuit 90, which receives an
output of transmission amplifier 50, and is controlled by antenna
selecting device 80 to provide the output of transmission amplifier
50 selectively to switch circuits 12.1-12.n corresponding to
antennas #1-#n, and particularly to the switch circuit
corresponding to the antenna of the highest reception level.
Structures other than the above are substantially the same as those
of radio base station 1000 of the first embodiment. The same
portions bear the same reference numbers, and description thereof
is not repeated.
FIG. 6 is a flowchart illustrating the operation of radio base
station of the modification of the first embodiment illustrated in
FIG. 5.
When the speech communication processing starts (step S200),
processing of establishing a traffic channel is performed, and the
speech communication starts (step S202).
Then, adaptive array reception of an uplink signal is performed
(step S204). The reception levels of the respective antennas are
measured, and memory 70 stores information of the antenna of the
highest reception level (step S206).
Based on the reception level information stored in memory 70, the
downlink signal is transmitted via the antenna of the highest
reception level (step S208).
When the transmission is completed, it is then determined whether
the speech communication state is finished or not (step S210). When
the speech communication is not finished, the processing returns to
step S204.
When it is determined that the speech communication is already
finished, the speech communication processing ends (step S212).
In the uplink communication, the above structure maintains the
communication quality by performing the adaptive array processing.
In the downlink communication, the above structure transmits the
signal by selectively using the antenna of the highest reception
level. Therefore, the radio base station can maintain the quality
of communication with the radio user terminal within the its own
cell.
SECOND EMBODIMENT
According to a second embodiment, the adaptive array processing is
performed in the uplink communication, and the non-directional
transmission is performed in the downlink communication. Further,
in the downlink communication, a transmission power is controlled
in accordance with a reception power in the uplink communication as
described below.
FIG. 7 is a conceptual view illustrating a transmission directivity
in the uplink communication according to the second embodiment.
FIG. 8 conceptually illustrates the transmission directivity in the
downlink communication as well as a range of waves.
In the uplink communication illustrated in FIG. 7, since the
reception with the directivity is performed by the adaptive array
processing, interference from the uplink communication by a user
terminal in the peripheral cell can be suppressed, and the lowering
of the communication quality of the user in the station's own cell
can be prevented.
Referring to FIG. 8, the transmission power in the downlink
communication is suppressed within a level allowing communication
of the user in the station's own cell so that the interference with
the peripheral cell is reduced, and the reduction in communication
quality of the peripheral cell user can be prevented. Further, in
the downlink communication, the adaptive array processing is not
performed so that the adaptive array processing circuit
corresponding to the downlink communication can be eliminated, and
therefore the installation cost of a base station 2000 can be
reduced.
FIG. 9 is a schematic block diagram illustrating a structure of
radio base station 2000 of the second embodiment illustrated in
FIGS. 7 and 8.
This structure differs from the structure of radio base station
1000 of the first embodiment illustrated in FIG. 3 in that radio
base station 2000 includes reception level measuring device 60,
which receives signals from respective antennas #1-#n, and measures
the reception levels thereof, memory 70 storing a conversion table,
which represents a relationship of the reception level measured by
reception level measuring device 60 with respect to the preset
reception level and the transmission power (and will be referred to
as a "reception level/transmission power conversion table"), and a
transmission power calculator 100, which calculates the
transmission power from the reception level of the predetermined
antenna (e.g., antenna #1) based on the reception
level/transmission power conversion table in memory 70, and
controls the output level of transmission amplifier 50.
For example, the reception level/transmission power conversion
table is prepared in advance by an experiment, in which the
transmission power required for the communication with the terminal
is determined with respect to the reception level, and is stored in
memory 70, although another manner may be employed.
Structures other than the above are substantially the same as those
of radio base station 1000 of the first embodiment illustrated in
FIG. 3. The same parts bear the same reference numbers, and
description thereof is not repeated.
FIG. 10 is a flowchart illustrating the operation of radio base
station 2000 of the second embodiment illustrated in FIG. 9.
Referring to FIG. 10, when the speech communication processing
starts (step S300), processing of establishing the traffic channel
is performed, and the speech communication starts (step S302).
Subsequently, the reception is performed by effecting the adaptive
array processing on the uplink signal (step S304), and memory 70
stores results obtained by measuring the reception levels of the
respective antennas (step S306).
For transmitting the signal to the user in the station's own cell,
the transmission power is determined from the reception level
information based on the reception level/transmission power
conversion table (step S308), and the downlink signal is
transmitted from predetermined antenna #1 with the transmission
power suppressed to the power level, which is estimated from the
reception level as the level required for the transmission (step
S310).
Subsequently, it is determined whether the speech communication is
already finished or not. If not, the processing returns to step
S304.
When it is determined in step S308 that the communication is
already finished, the speech communication processing ends (step
S314).
According to the structures described above, it is possible to
control the uplink communication and downlink communication as
illustrated in FIGS. 7 and 8.
MODIFICATION OF SECOND EMBODIMENT
FIG. 11 is a schematic block diagram illustrating a structure of a
radio base station 2200, which is a modification of radio base
station 2000 of the second embodiment already described with
reference to FIG. 9.
The structure of radio base station 2200 differs from that of radio
base station 2000 of the second embodiment illustrated in FIG. 9 in
that switch circuits 12.1-12.n are provided corresponding to
respective antennas #1-#n for switching transmission paths of the
signals to and from the antennas in the transmission and reception
operations.
Further, radio base station 2200 includes antenna selecting device
80 for selecting the antenna of the highest reception level in
accordance with the reception levels of the respective antennas
stored in memory 70, and switch circuit 90 for providing the output
of transmission amplifier to one of switch circuits 12.1-12.n,
which corresponds to the antenna selected by antenna selecting
device 80.
Other structures are the same as those of radio base station 2000
of the second embodiment illustrated in FIG. 9. The same portions
bear the same reference numbers, and description thereof is not
repeated.
FIG. 12 is a flowchart illustrating the operation of radio base
station 2200 of the modification of the second embodiment
illustrated in FIG. 11.
Referring to FIG. 12, when the speech communication processing
starts (step S400), processing of establishing a traffic channel is
performed, and the speech communication starts (step S402).
Subsequently, adaptive array reception of an uplink signal is
performed, and the signal sent from the user is separated (step
S404). The reception levels of the respective antennas are
measured, and memory 70 stores information of the reception levels
(step S406).
When the signal is to be transmitted to the user's terminal, the
transmission power, which is required for the transmission, is
determined from the reception level information according to the
reception level/transmission power conversion table in memory 70
(step S408). Further, the antenna of the highest reception level is
selected from the reception level information (step S410), and the
downlink signal is transmitted from the selected antenna with the
transmission power determined in step S408 (step S412).
Subsequently, it is determined whether the speech communication is
already finished or not (step S414). When the speech communication
processing is not yet finished, the processing returns to step
S404.
When it is determined in step S414 that the speech communication is
already finished, the speech communication processing ends (step
S416).
The structure described above can maintain the communication
quality in both the uplink communication and downlink
communication, and can suppress the interference with the
peripheral cell.
THIRD EMBODIMENT
According to the structure of the second embodiment already
described, the radio base station suppresses the transmission power
in accordance with the reception level related to the terminal in
the station's own cell. However, the level of the interference
power provided from the peripheral cell may be low, e.g., in such a
case that a distance to a base station of the peripheral cell is
relatively large. If the above level is low, it is not necessary in
some cases to suppress the transmission power level depending on
only the reception level related to the terminal in the station's
own cell.
In the third embodiment, the adaptive array processing is performed
in the uplink communication, and the non-directional transmission
is performed in the downlink communication. Further, the downlink
transmission power is controlled in accordance with the uplink
reception power and the carrier sense level.
FIGS. 13 16. are conceptual views illustrating a method of
controlling the transmission power and the transmission directivity
according to the third embodiment.
FIGS. 13 and 14 illustrate a state, in which a distance to the
peripheral cell is relatively short, and interference with a
terminal PS2 in the peripheral cell may cause a problem.
Referring to FIG. 13, a radio base station 3000 of the third
embodiment performs the adaptive array processing in the uplink
communication operation of receiving the signal from terminal
device PS1 of the user in the station's own cell. Therefore,
interference in the uplink communication can be suppressed so that
lowering of communication quality of the user in the station's own
cell can be prevented.
Referring to FIG. 14, the downlink transmission power in the
downlink communication is suppressed to the level allowing
communication of the user in the station's own cell. Therefore, the
interference with the peripheral cell is reduced, and the lowering
of the communication quality of the user in the peripheral cell can
be prevented.
FIGS. 15 and 16 illustrate a state, in which the distance to the
peripheral cell is relatively long, and the interference with
terminal PS2 in the peripheral cell may cause a problem.
FIG. 15 is a conceptual view illustrating a manner of suppressing
interference in the uplink communication.
In FIG. 15, a peripheral cell using the same frequency at the same
time is remote from radio base station 3000. In this state, radio
base station 3000 performs the reception with the transmission
directivity when the uplink communication is performed with radio
terminal PS1 of the user in the station's own cell. Therefore, it
is possible to suppress the interference from the peripheral cell,
and thereby to maintain the communication quality of the user in
the station's own cell.
In the downlink communication, as illustrated in FIG. 16,
processing is performed based on the reception level of the signal,
which is sent from user terminal PS1 in the station's own cell, to
suppress the downlink transmission power to an extent allowing
communication by the peripheral cell user. The extent of this
suppression is controlled in accordance with the level of the
carrier sense sensing the level of the signal provided from the
peripheral cell, and the suppression is not performed to an extent
exceeding the necessary extent. For example, it may be determined
that the suppression of the transmission level can be eliminated
without substantially affecting the communication with terminal PS2
in the peripheral cell. In this case, the downlink communication
may be performed with the transmission power of the original or
initial setting value.
Thus, a margin can be ensured in the transmission power of the
station's own cell user, and a high resistance to fading variations
can be ensured. Therefore, it is possible to prevent deterioration
in downlink communication quality of the station's own cell
user.
FIG. 17 is a schematic block diagram illustrating the structure of
radio base station 3000 of the third embodiment illustrated in
FIGS. 13 to 16.
This structure differs from the structure of radio base station
2000 of the second embodiment illustrated in FIG. 9 in that
reception level measuring device 60 measures not only the reception
level of the signal coming from terminal PS1 in the station's own
cell but also the reception level of the signal coming from
terminal PS2 in the peripheral cell, and stores them in memory 70.
The "reception level/transmission power conversion table" stored in
memory 70 is prepared to define the transmission power level
corresponding to not only the reception level of the signal coming
from the terminal in the station's own cell but also the received
level of the signal coming from the peripheral cell.
For example, the "reception level/transmission power conversion
table" is configured in advance by an experiment similarly to the
second embodiment, and more specifically is configured such that,
when the reception level of the signal coming from the peripheral
cell takes a predetermined value (which is represented by PW1 in
the following description) or more, the transmission power level
initially taking a predetermined initial value is successively
suppressed in accordance with increase in reception level of the
signal coming from terminal PS1 in the station's own cell. It is
also configured such that, when the reception level of the signal
coming from the peripheral cell is lower than predetermined value
PW1, the transmission power level maintains the predetermined
initial value independently of the reception level of the signal
coming from terminal PS1 in the station's own cell.
The structure of the "reception level/transmission power conversion
table" is not restricted to the above, and it is merely required to
suppress an influence, which is exerted by the downlink
communication with terminal PS1 in the station's own cell on the
communication between terminal PS2 in the peripheral cell and base
station CS2 in the peripheral cell. For example, the table may be
configured such that, when the reception level obtained from the
peripheral cell is lower than predetermined value PW1, the
transmission power level increases from the predetermined initial
value in accordance with the reception level of the signal coming
from terminal PS1 in the station's own cell.
Further, transmission power calculator 100 controls the output
level of transmission amplifier 50 by calculating the transmission
power based on the reception level of the predetermined antenna
(e.g., antenna #1) according to the reception level transmission
power conversion table in memory 70, which is preset as described
above.
Other structures are the same as those of radio base station 2000
of the second embodiment illustrated in FIG. 9. The same portions
bear the same reference numbers, and description thereof is not
repeated.
FIG. 18 is a flowchart illustrating an operation of radio base
station 3000 of the third embodiment illustrated in FIG. 17.
Referring to FIG. 18, when the speech communication processing
starts (step S500), reception level measuring device 60 measures
the interference power applied from the peripheral cell based on
the reception signals sent from antennas #1-#n, and stores it in
memory 70 (step S502). Subsequently, processing of establishing the
traffic channel is performed, and the speech communication starts
(step S504).
Then, the uplink signal is received by performing the adaptive
array processing (step S506), and memory 70 stores measured
reception levels of the respective antennas (step S508).
For transmitting the signal to the user in the station's own cell,
the transmission power is determined according to the reception
level/transmission power conversion table and based on the
information thus stored in memory 70, i.e., based on the
information of the interference power applied from the peripheral
cell and the information of the reception level obtained from the
terminal in the station's own cell (step S510). The transmission
power is controlled to attain the power level, which is required
for transmission according to estimation from the interference
power and the reception level, and the downlink signal is sent from
fixed antenna #1 with the transmission power thus calculated (step
S512).
Subsequently, it is determined whether the speech communication is
already finished or not. When the speech communication processing
is not finished, the processing returns to step S506.
When it is determined in step S514 that the speech communication is
already finished, the speech communication processing ends (step
S516).
The structure described above can control the uplink communication
and downlink communication as already described with reference to
FIGS. 13 to 16.
MODIFICATION OF THIRD EMBODIMENT
FIG. 19 is a schematic block diagram illustrating a structure of a
radio base station 3200, which is a modification of radio base
station 3000 of the third embodiment illustrated in FIG. 17.
The structure of radio base station 3200 differs from that of radio
base station 3000 of the third embodiment in that switch circuits
12.1-12.n are provided for antennas #1-#n, respectively, and signal
transmission paths to or from the antennas in the transmission and
reception operations are switched.
Further, radio base station 3200 includes antenna selecting device
80, which selects the antenna of the highest reception level in
accordance with the reception level information in memory 70, i.e.,
the reception levels of respective antennas related to terminal PS1
in the station's own cell, and switch circuit 90 providing the
output of transmission amplifier 50 to one of switch circuits
12.1-12.n corresponding to the antenna, which is selected by the
antenna selecting device 80.
Other structures are the same as those of radio base station 3000
of the third embodiment illustrated in FIG. 17. The same portions
bear the same reference numbers, and description thereof is not
repeated.
FIG. 20 is a flowchart illustrating an operation of radio base
station 3200 of the third embodiment illustrated in FIG. 19.
Referring to FIG. 20, when the speech communication processing
starts (step S600), reception level measuring device 60 measures
the interference power applied from the peripheral cell based on
the reception signals sent from antennas #1-#n, and stores it in
memory 70 (step S602). Subsequently, processing of establishing the
traffic channel is performed to start the speech communication
(step S604).
Then, the uplink signal is received by performing the adaptive
array processing (step S606), and measured reception levels of the
respective antennas are stored in memory 70 (step S608).
For transmitting the signal to the user in the station's own cell,
the transmission power is determined according to the reception
level/transmission power conversion table and based on the
information thus stored in memory 70, i.e., based on the
information of the interference power applied from the peripheral
cell and the information of the reception level obtained from the
terminal in the station's own cell (step S610). Antenna selecting
device 80 selects the antenna (e.g., antenna #1) of the highest
reception level (step S612).
Subsequently, the downlink signal is transmitted from antenna #1 of
the highest reception level with the determined transmission power
(step S614).
Subsequently, it is determined whether the speech communication is
already finished or not (step S616). When the speech communication
processing is not finished, the processing returns to step
S606.
When it is determined in step S616 that the speech communication is
already finished, the speech communication processing ends (step
S616).
The structure described above can control the uplink communication
and downlink communication as already described with reference to
FIGS. 13 to 16. Further, the downlink communication with terminal
PS1 in the station's own cell is performed with the antenna of the
highest reception level so that the quality of communication in the
station's own cell can be kept high.
As described above, the adaptive array reception is performed in
the uplink communication with the terminal in the station's own
cell so that the reception can be performed while suppressing the
interference from the peripheral cell. Also, the non-directional
transmission is performed in the downlink communication so that the
structure can be simple and inexpensive.
Preferably, according to the invention, the transmission power in
the downlink communication is controlled to suppress the influence
on the peripheral cell. Therefore, the communication quality of the
whole system can be further improved.
INDUSTRIAL APPLICABILITY
Since the adaptive array reception is performed in the uplink
communication with the terminal in the station's own cell, the
reception can be performed while suppressing the interference from
the peripheral cell so that the invention can be effectively
applied to the adaptive array radio device.
* * * * *